Brewster's difficulties since arriving at Bramall Lane have been much publicised and he has started just three league games this term and has yet to break his duck at league level for United.
McBurnie's only goal in ten appearances in all competitions arrived in the recent EFL Cup tie with Southampton, with six of his eight Championship appearances having come from the bench.
His last league goal for the club was last December.
Both players were unused substitutes in the midweek loss at Middlesbrough
Jokanovic, whose side are seeking to hit back from a disappointing night at the Riverside Stadium at joint-leaders Bournemouth on Saturday, said: "At the moment, we have chosen how we want to play, they need to trust and work hard and wait for the moment when I need them, and they must be ready for this moment.
"It is my decision who I choose, I tried to make some movement and find a way to come back in the (Middlesbrough) game so I made the decision to use some players.
"I thought about McBurnie and Rhian, but I took a different option, but I could use them in games ahead of us.
"I am not coaching only 11 players. The questions are normal but I must take my decision for games ahead of us, we will take what we believe is the best decision for the team."
United were overpowered physically in their loss on Teesside against strong opponents, but Jokanovic says that his side face a much different challenge against a Bournemouth side, whose style is totally different.
Jokanovic added: "They (Bournemouth) have started better than us, the question is who will finish better. We cannot give up, they cannot relax after a good start either. A lot of the space is ahead of both teams.
"It’s a completely different challenge (to Boro), a different team and style of play.
"We will try to analyse their strengths and weaknesses. They are without any defeats but we want to be fighting with them and be at their level, fighting for similar targets. It’s a great chance for us to check where we are, to try and push for three points."